Question: Tiffany starts counting at 35, and she counts by fours. If 35 is the 1st number that Tiffany counts. what is the 13th number that she counts?
Explanation: What is the first number that she counts? $35$ What is the second number that she counts? $\begin{align*}&35 + 4 \\ &= 39\end{align*}$ What is the third number that she counts? $\begin{align*}&35 + 4 + 4 \\ &= 35 + (2 \times 4) \\ &= 43\end{align*}$ What is the 13th number that she counts? $\begin{align*}&35 + (12\times4) \\ &= 35 + 48 \\ &= 83\end{align*}$